Problem: Evaluate the following expression when $a = 10$ and $b = 5$. $7$ $a$ $ + 7$ $b$ $ - 5$
Answer: Substitute $10$ for ${a}$ and $5$ for ${b}$ $ = 7{(10)} + 7{(5)} - 5 $ $ = 70 + 35 - 5 $ $ = 100$